Genesis of continental crust: evidence from island arcs, granulites, and exospheric processes

Abstract

Although the average granodioritic chemical composition of the upper crust is well established, the nature of the higher metamorphic grade (amphibolite-granulite) lower crust is less certain, and the character of the crust-mantle boundary or Moho is variable beneath different provinces. Many granulite terrains appear to represent the quartzofelspathic residues of dehydration melting with fractional loss of a silicic melt. In contrast, most granulite-eclogite xenolith suites seem to be variably contaminated (with preexisting crust) Proterozoic and younger, under- and intraplated basic magmas and associated cumulates. -from Authors